New Finds of Skeletal Fossils in the Terminal Neoproterozoic of the Siberian Platform and Spain
New Finds of Skeletal Fossils in the Terminal Neoproterozoic of the Siberian Platform and Spain
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DOI：
10.4202/app.2010.0074
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发表时间：
2012-03
期刊：
影响因子：
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通讯作者：
A. Zhuravlev;E. Liñán;J. A. G. Vintaned;F. Debrenne;A. B. Fedorov
中科院分区：
文献类型：
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作者：
A. Zhuravlev;E. Liñán;J. A. G. Vintaned;F. Debrenne;A. B. Fedorov
目前的范式只接受生物矿化程度较弱的动物的存在，仅略高于新元古代末期(埃迪卡拉纪)的低后生动物组织等级，以及后来早寒武世爆发的骨骼良好的动物。本文报道了西班牙和俄罗斯(西伯利亚地台)上埃迪卡拉统(553-542 Ma)碳酸盐岩中主要为钙质壳化石的新组合。在西伯利亚地台东南部的尤多马群中发现了有问题的生物Cloudina，在西班牙几个省的新元古代末期发现了不同的骨骼类群。埃迪卡拉纪骨骼化石Cloudina和Namacalatus的形态和显微结构的新数据表明，新元古代骨骼生物已经相当先进。在这个时间间隔内，全世界总共记录了至少15个骨骼后生动物属。这一数字与已知的早寒武世基底的数字相当。这些数据表明，新元古代末期的骨骼盛开是寒武纪辐射的真正前兆。Cloudina是西伯利亚地台上最古老的动物，具有矿化的骨骼，它是乌斯特-尤多马组最上层的埃迪卡拉纪地层的特征。在西伯利亚，Cloudina与寒武纪的小型骨骼化石共生，在西班牙，含Cloudina的碳酸盐岩和其他埃迪卡拉纪骨骼化石与含有丰富的新元古代末期遗迹化石组合的地层相间。这些共同处理的发现提供了对世界各地新元古代-下寒武统过渡性地层进行对比的可能性。这种相关性与现有的同位素和放射性数据相吻合，并表明典型的埃迪卡拉纪壳体化石没有越过前寒武纪-寒武纪的界线。
A current paradigm accepts the presence of weakly biomineralized animals only, barely above a low metazoan grade of organization in the terminal Neoproterozoic (Ediacaran), and a later, early Cambrian burst of well skeletonized animals. Here we report new assemblages of primarily calcareous shelly fossils from upper Ediacaran (553–542 Ma) carbonates of Spain and Russia (Siberian Platform). The problematic organism Cloudina is found in the Yudoma Group of the southeastern Siberian Platform and different skeletal taxa have been discovered in the terminal Neoproterozoic of several provinces of Spain. New data on the morphology and microstructure of Ediacaran skeletal fossils Cloudina and Namacalathus indicate that the Neoproterozoic skeletal organisms were already reasonably advanced. In total, at least 15 skeletal metazoan genera are recorded worldwide within this interval. This number is comparable with that known for the basal early Cambrian. These data reveal that the terminal Neoproterozoic skeletal bloom was a real precursor of the Cambrian radiation. Cloudina, the oldest animal with a mineralised skeleton on the Siberian Platform, characterises the uppermost Ediacaran strata of the Ust'-Yudoma Formation. While in Siberia Cloudina co-occurs with small skeletal fossils of Cambrian aspect, in Spain Cloudina-bearing carbonates and other Ediacaran skeletal fossils alternate with strata containing rich terminal Neoproterozoic trace fossil assemblages. These finds treated together provide a possibility to correlate transitional Neoproterozoiclower Cambrian strata around the world. Such a correlation concurs with available isotope and radiometric data and indicates that typical Ediacaran shelly fossils have not crossed the Precambrian—Cambrian boundary.